Group III nitride semiconductors have a wide band gap, and therefore, they are widely used as materials for luminescent devices, such as blue, green, and other color LEDs (light-emitting diodes), LDs (laser diodes), and the like. Such luminescent devices are configured by laminating a p-type semiconductor layer (p-type layer) and an n-type semiconductor layer (n-type layer) by the epitaxial growth process.
In order to manufacture such a structure with a good quality being provided at a low cost, a p-type layer and an n-type layer are epitaxially grown on an epitaxial substrate made of a material other than the group III nitride semiconductor in general. In this case, the type of material which can be used as an epitaxial substrate for obtaining a semiconductor layer with a particularly good quality is limited. For example, gallium nitride (GaN), a typical group III nitride semiconductor, can be grown on a dissimilar epitaxial substrate formed of SiC, sapphire, or the like, by the MOCVD (Metal Organic Chemical Vapor Deposition) process, the HVPE (Hydride Vapor Phase Epitaxy) process, or the like.
However, since sapphire is an insulator, it is required to provide two electrodes on the top face of a semiconductor layer laminated thereon, which has caused problems that the effective luminescent area is narrowed down for a given substrate area, in comparison with the conductive substrate, and both electrodes being provided on the same face locally increases the current density, resulting in the device being deteriorated due to the heat generated.
Then, in Patent Document 1, there is disclosed a method for manufacturing a luminescent device utilizing the laser lift-off technology, and in Patent Document 2, there is disclosed a method for manufacturing a luminescent device utilizing the chemical lift-off technology. With these manufacturing methods, an n-type layer, a p-type layer, and a p-side electrode are sequentially formed on a sapphire substrate, which is followed by newly forming a conductive supporting substrate on the side of the p-side electrode, and peeling-off the sapphire substrate.
With a vertical type luminescent device based on such a lift-off technology, a supporting substrate made of another material which is optimized in thermal conductivity, and the like, can be used, whereby a high heat dissipation and reliability can be obtained.